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themuethemue
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Improve jittering and testing
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‎.github/workflows/build.yml‎

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@@ -18,7 +18,7 @@ jobs:
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- name: Set up Go
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uses: actions/setup-go@v4
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with:
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go-version: "1.22"
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go-version: "1.24"
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- name: Install dependencies
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run: |

‎CHANGELOG.md‎

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# Changelog
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### v0.4.0
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- Update to Go 1.24
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- Change jittering to use interval, offset, and timeouts
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- Change tests to verify package
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### v0.3.0
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- Migrated to Go 1.20
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- Update to Go 1.20
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- Simplified `Throttle` implementation
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- Migrated to Go 1.18
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### v0.2.0 (2022-03-04)
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- Added Throttle
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- Add Throttle
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### v0.1.1 (2021-09-07)
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- Fixed documentation
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- Fixe documentation
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### v0.1.0 (2021-09-07)
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- Migrated Wait code from together library
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- Migrate Wait code from together library

‎LICENSE‎

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BSD 3-Clause License
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Copyright (c) 2019-2024, Frank Mueller / Tideland / Oldenburg / Germany
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Copyright (c) 2019-2025, Frank Mueller / Tideland / Oldenburg / Germany
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All rights reserved.
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Redistribution and use in source and binary forms, with or without

‎doc.go‎

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// Tideland Go Wait
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//
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// Copyright (C) 2019-2024 Frank Mueller / Tideland / Oldenburg / Germany
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// Copyright (C) 2019-2025 Frank Mueller / Tideland / Oldenburg / Germany
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//
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// All rights reserved. Use of this source code is governed
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// by the new BSD license.

‎go.mod‎

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module tideland.dev/go/wait
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go 1.22
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go 1.24
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require (
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golang.org/x/time v0.5.0
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tideland.dev/go/audit v0.7.0
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tideland.dev/go/asserts v0.0.0
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)

‎go.sum‎

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golang.org/x/time v0.5.0 h1:o7cqy6amK/52YcAKIPlM3a+Fpj35zvRj2TP+e1xFSfk=
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golang.org/x/time v0.5.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
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tideland.dev/go/audit v0.7.0 h1:lr4LkNu7i5qLJuqQ6lUfnt0J09anZNfrdXdB1I9JlTs=
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tideland.dev/go/audit v0.7.0/go.mod h1:Jua+IB3KgAC7fbuZ1YHT7gKhwpiTOcn3Q7AOCQsrro8=

‎jitter.go‎

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// Tideland Go Wait
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//
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// Copyright (C) 2019-2025 Frank Mueller / Tideland / Oldenburg / Germany
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//
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// All rights reserved. Use of this source code is governed
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// by the new BSD license.
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package wait // import "tideland.dev/go/wait"
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//--------------------
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// IMPORTS
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//--------------------
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import (
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"context"
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"crypto/rand"
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"math"
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"math/big"
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"time"
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)
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// MakeJitteringTicker returns a ticker signalling in jittering intervals. This
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// avoids converging on periadoc behavior during condition check. The returned
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// interval jitters inside the given interval and starts with the given offset.
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// The ticker stops after reaching the timeout.
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func MakeJitteringTicker(interval, offset, timeout time.Duration) TickerFunc {
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start := time.Now()
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deadline := start.Add(timeout)
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// Sanitize
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if interval < time.Millisecond {
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interval = time.Millisecond
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}
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if offset < 0 {
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offset = 0
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}
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if interval > time.Duration(math.MaxInt64)-offset {
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interval = time.Duration(math.MaxInt64) - offset
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}
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next := start
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changer := func(_ time.Duration) (time.Duration, bool) {
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now := time.Now()
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if now.After(deadline) {
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return 0, false
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}
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// Generate jitter in range [0, interval)
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jitterRange := interval
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if deadline.Sub(now) < offset+jitterRange {
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jitterRange = deadline.Sub(now) - offset
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if jitterRange < 1 {
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return 0, false
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}
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}
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58+
bigInt, err := rand.Int(rand.Reader, big.NewInt(jitterRange.Nanoseconds()))
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if err != nil {
60+
return 0, false
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}
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jitter := time.Duration(bigInt.Int64())
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wait := offset + jitter
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66+
next = next.Add(wait)
67+
delay := max(time.Until(next), 0)
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return delay, true
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}
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return MakeGenericIntervalTicker(changer)
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}
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// WithJitter is convenience for Poll() with MakeJitteringTicker().
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func WithJitter(
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ctx context.Context,
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interval, offset, timeout time.Duration,
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condition ConditionFunc,
79+
) error {
80+
return Poll(
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ctx,
82+
MakeJitteringTicker(interval, offset, timeout),
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condition,
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)
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}
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// EOF

‎jitter_test.go‎

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// Tideland Go Wait - Unit Tests
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//
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// Copyright (C) 2019-2025 Frank Mueller / Tideland / Oldenburg / Germany
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//
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// All rights reserved. Use of this source code is governed
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// by the new BSD license.
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8+
package wait_test // import "tideland.dev/go/wait"
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//--------------------
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// IMPORTS
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//--------------------
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14+
import (
15+
"context"
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"testing"
17+
"time"
18+
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"tideland.dev/go/asserts/verify"
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"tideland.dev/go/wait"
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)
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//--------------------
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// TESTS
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//--------------------
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// TestPollWithJitter tests the polling of conditions in a maximum
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// number of intervals.
30+
func TestPollWithJitter(t *testing.T) {
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timestamps := []time.Time{}
32+
err := wait.Poll(
33+
context.Background(),
34+
wait.MakeJitteringTicker(
35+
50*time.Millisecond,
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10*time.Millisecond,
37+
1250*time.Millisecond,
38+
),
39+
func() (bool, error) {
40+
timestamps = append(timestamps, time.Now())
41+
if len(timestamps) == 10 {
42+
return true, nil
43+
}
44+
return false, nil
45+
},
46+
)
47+
verify.NoError(t, err)
48+
verify.Length(t, timestamps, 10)
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50+
t.Logf("Timestamps for first test: %v", timestamps)
51+
for i := range 9 {
52+
diff := timestamps[i+1].Sub(timestamps[i])
53+
t.Logf("Diff %d: %v", i, diff)
54+
// According to implementation, jitter is within [offset, offset+interval]
55+
verify.InRange(t, 10*time.Millisecond, 60*time.Millisecond, diff)
56+
}
57+
58+
timestamps = []time.Time{}
59+
err = wait.WithJitter(
60+
context.Background(),
61+
50*time.Millisecond,
62+
10*time.Millisecond,
63+
1250*time.Millisecond, func() (bool, error) {
64+
timestamps = append(timestamps, time.Now())
65+
if len(timestamps) == 10 {
66+
return true, nil
67+
}
68+
return false, nil
69+
})
70+
verify.NoError(t, err)
71+
verify.Length(t, timestamps, 10)
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73+
t.Logf("Timestamps for second test: %v", timestamps)
74+
for i := 1; i < 10; i++ {
75+
diff := timestamps[i].Sub(timestamps[i-1])
76+
t.Logf("Diff %d: %v", i, diff)
77+
// According to implementation, jitter is within [offset, offset+interval]
78+
verify.InRange(t, 10*time.Millisecond, 60*time.Millisecond, diff)
79+
}
80+
81+
timestamps = []time.Time{}
82+
err = wait.Poll(
83+
context.Background(),
84+
wait.MakeJitteringTicker(
85+
50*time.Millisecond,
86+
10*time.Millisecond,
87+
1250*time.Millisecond),
88+
func() (bool, error) {
89+
timestamps = append(timestamps, time.Now())
90+
return false, nil
91+
},
92+
)
93+
verify.ErrorContains(t, "exceeded", err)
94+
verify.InRange(t, len(timestamps), 10, 25)
95+
96+
timestamps = []time.Time{}
97+
err = wait.Poll(
98+
context.Background(),
99+
wait.MakeJitteringTicker(
100+
50*time.Millisecond,
101+
10*time.Millisecond,
102+
1000*time.Millisecond),
103+
func() (bool, error) {
104+
timestamps = append(timestamps, time.Now())
105+
return false, nil
106+
},
107+
)
108+
verify.ErrorContains(t, "exceeded", err)
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// This ticker has a non-zero offset, so it should run at least once before timing out
110+
verify.True(t, len(timestamps) > 0)
111+
112+
timestamps = []time.Time{}
113+
ctx, cancel := context.WithTimeout(context.Background(), 350*time.Millisecond)
114+
defer cancel()
115+
err = wait.Poll(
116+
ctx,
117+
wait.MakeJitteringTicker(
118+
50*time.Millisecond,
119+
10*time.Millisecond,
120+
1000*time.Millisecond),
121+
func() (bool, error) {
122+
timestamps = append(timestamps, time.Now())
123+
return false, nil
124+
},
125+
)
126+
verify.ErrorContains(t, "exceeded", err)
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// Context cancellation should still allow some ticks to happen
128+
verify.True(t, len(timestamps) > 0)
129+
}
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// EOF

‎throttle.go‎

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@@ -1,6 +1,6 @@
11
// Tideland Go Wait
22
//
3-
// Copyright (C) 2019-2023 Frank Mueller / Tideland / Oldenburg / Germany
3+
// Copyright (C) 2019-2025 Frank Mueller / Tideland / Oldenburg / Germany
44
//
55
// All rights reserved. Use of this source code is governed
66
// by the new BSD license.

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